“I am closely watching this. This standard is the real test of how serious the Obama climate action plan really is,” said Qi Ye, director of the Climate Policy Center at Tsinghua University in China. The university is one of about half a dozen institutions that the Chinese government has tasked with immediately analyzing the new rule, according to Chinese experts.

China and the United States, the world’s two largest economies and greenhouse gas polluters, are locked in a stalemate over global warming. While today China pollutes more than the United States, Chinese officials insist that, as a developing economy, China should not be forced to take carbon-cutting actions. China has demanded that the United States, as the world’s historically largest polluter, go first. Chinese policy experts say that Mr. Obama’s regulation could end that standoff.

“If the standard is really stringent, that will make a difference in the domestic debate in China,” Mr. Qi said.

Mr. Qi said that while he did not expect the Chinese government to publicly comment on the E.P.A. rule, a strong regulation — like one that led to a 20 percent cut in coal plant pollution — could stimulate policy changes. “It will have an impact,” he said.